1. Technical Field
Example embodiments of the present invention relate to a method of dimming light sources, a light source apparatus for performing the method, and a display apparatus having the light source apparatus. More particularly, example embodiments of the present invention relate to a method for independently dimming a plurality of light-emitting blocks, a light source apparatus for performing the method, and a display apparatus having the light source apparatus.
2. Related Art
Generally, a liquid crystal display (LCD) apparatus includes an LCD panel displaying an image using optical transmittance of liquid crystal molecules and a backlight assembly disposed below the LCD panel to provide the LCD panel with light.
The typical LCD panel includes an array substrate, a color filter substrate, and a liquid crystal layer. The array substrate includes a plurality of pixel electrodes and a plurality of thin-film transistors (TFTs) electrically connected to the pixel electrodes. The color filter substrate faces the array substrate and has a common electrode and a plurality of color filters. The liquid crystal layer is interposed between the array substrate and the color filter substrate.
When an electric field generated between the pixel electrode and the common electrode is applied to the liquid crystal layer, an arrangement of liquid crystal molecules of the liquid crystal layer is altered to change optical transmissivity, so that an image is displayed. For example, the LCD panel may realize a white image of a high luminance when an optical transmittance is increased to a maximum, and the LCD panel realizes a black image of a low luminance when the optical transmittance is decreased to a minimum.
The LCD apparatus may, however, have a disadvantage of glare in comparison with other types of display apparatuses such as a cathode ray tube (CRT), or a plasma display panel (PDP), for example. The LCD apparatus requires an external light in order to display an image since an LCD panel does not emit light by itself. Thus, the LCD apparatus may have different luminance distribution characteristics than those of the CRT or the PDP. A user may experience eye fatigue due to the different luminance distribution characteristics.
Recently, in order to prevent the contrast ratio of an image from being decreased and to minimize power consumption, a method of local dimming of a light source has been developed, which controls amounts of light according to position to drive a light source. In the method of local dimming of the light source, the light source is divided into a plurality of light-emitting blocks to control the amounts of light of the light-emitting blocks in correspondence with dark and light areas of a display area of the LCD panel corresponding to the light-emitting blocks. For example, a light-emitting block corresponding to a display area displaying a black image is driven at a low luminance (e.g., turned off), and a light-emitting block corresponding to a display area displaying a white image is driven at a high luminance. The local dimming method may be employed to solve the disadvantage of glare. The local dimming method may have characteristics capable of controlling luminance by emitting blocks, so that an effect such as driving characteristics of a CRT or a PDP may be realized.
Recently, in order to enhance contrast ratio (CR), to decrease power consumption, and to increase color reproducibility, interest in local dimming has increased in products employing light-emitting diodes (LED). For example, a full screen area is divided into a plurality of blocks having uniform size to compensate gamma characteristics generated due to light leakage of an LCD panel through each block luminance or color dimming, so that the CR is enhanced. Moreover, the color reproducibility is increased and the power consumption is reduced.